The Crystal Structure of Vlodavetsite, AlCa2(SO4)2F2Cl·4H2O

G. L. Starova, S. K. Filatov, G. L. Matusevich and V. S. Fundamensky
Department of Crystallography, State University, Univers. emb. 7/9, St. Petersburg, 199034, Russia
NPP Burevestnik, St. Petersburg, Russia

Absract: The crystal structure of vlodavetsite, AlCa2(SO4)2F2Cl·4H2O, has been determined, space group I4/m, a = 6.870(1), c = 13.342(2) Å, Z = 2, Dx = 2.35 g/cm3. The polyhedron cation chains are parallel to [001] and consist of couples of distorted Ca octahedra alternating with one distorted Al octahedron rotated through 24° with respect to the former. The chains are linked by SO4-tetrahedra so that all of the four tetrahedron oxygen atoms take part in coordination of Ca atoms to form a distorted octahedron with Cl and F atoms. The Al coordination polyhedron consists of two F atoms and four oxygen atoms belonging to water molecules. There is a specific interaction via hydrogen bonds between oxygen atoms of SO4-tetrahedra and water molecules.

Keywords: vlodavetsite • crystal structure

Mineralogical Magazine; March 1995 v. 59; no. 394; p. 159-162; DOI: 10.1180/minmag.1995.59.394.16
© 1995, The Mineralogical Society
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